Optic nerve chloramphenicol

The optic nerve is of interest here because some drugs are toxic to this tissue.The antibiotics chloramphenicol, ethambutol, streptomycin, and sulfonamides can cause optic neuritis. Vitamin A, especially in large doses, can result in papilledema. Digitalis can cause retrobulbar neuritis (see Chapter 35). 

The precise mechanism by which chloramphenicol produces optic neuritis is unknown.Although the view is not substantiated, several authors have proposed that chloramphenicol may induce optic neuropathy by causing a vitamin deficiency. Genetic fectors may be involved, and it has also been hypothesized that chloramphenicol may be biotransformed into degradation products that are potentially toxic to the optic nerve. 

A review of certain chemicals is essential. Ethylene glycol is an antifreeze used for gasoline engines and may produce somnolence, imreactive pupils, disc swelling, and kidney failure. Systemic lead poisoning produces headaches, coma, cranial nerve palsies, and papilledema. Wood alcohol, or methanol, may produce severe toxic neuropathy and disc edema. Drugs known to produce toxic optic neuropathy include amiodarone (an antiar-rhythmic), quinine, aminoquinolines, ibuprofen, ethambutol, isoniazid, and chloramphenicol. 

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